Andy's Astronomy

I picked up some new batteries for the laser collimator today.  One of the original cells was at 1.4V and the other two were at 1.1V.  I'm always suspicious of batteries that come packaged with something anyway.  With the new batteries installed, I was able to adjust my laser so when turned on my adjustment jig, the beam only moved about 1/8" when measured 20 feet away.  Close enough for me.

Before collimating the scope, I decided to do a couple of quick and simple mods.

I carefully removed the secondary by unscrewing the center screw and removed the metal washer.  Be careful when you do this and tip the scope horizontal.  There is a spring on the screw as well and you don't want that to fall on the primary.  I then traced the metal washer on plastic from a milk jug and cut out two duplicates.  The two plastic washers go back on the screw instead of the metal washer, then carefully put the secondary back on.

I also replaced the secondary collimation screws with M4 x 25mm allen head bolts, which are easy to adjust by hand.

After all of that, I adjusted my secondary position by eyeballing it through the finder opening.  I don't have a sight tube yet, so I can't adjust it very accurately.  I wanted to make a sight tube out a film canister, but good luck finding one of those in the digital age.  No one has them anymore.  YouTube videos helped out on figuring out how to adjust things.

I popped the laser in the finder and adjusted the secondary collimation get the laser's dot right in the middle of the center donut on the primary.

The spot from the laser isn't really a dot, it's more of an oval, so I used the "barlowed laser" technique described on many websites and videos.  You put the laser in a barlow, which diffuses the beam.  Rather than reflecting back the dot of the laser, it reflects an image of the center donut from the primary.

Loosen up the three white locking knobs on the primary before adjusting the black collimating knobs.  Center the image of the donut over the hole in the middle of the collimator.  First adjust things with the scope horizontal, then move it vertical to check that everything is still good.  Once you're satisfied, turn the white knobs so they are barely touching the back of the mirror cell.  Don't put any pressure on the white knobs or you could distort the mirror cell.